Antioxidant



Patented Nov. 22, 1932 UNITED STATES PATENTOFFICE JAN T PPEMA, or AKRON, OHIO, assrenon 'ro THE GOODYEAR TIRE a RUBBER COMPANY, OF AKRON, care, A CORPORATION or OHIO ANTIOXIDANT' N 0 Drawing. 7

My invention relates to thetreatment of a when introduced into rubber compounds the eifect of greatly slowing up or. retarding the action of air and light upon the rubber, there by materially prolonging the life of articles formed thereof. 7 Most of the compounds thus far proposed have, however, been obj ectionable'for variousreasons. Certain of them, while very effective as antioxidants, possess highly disagreeable odors that are of.- fensive or even poisonous to workmen employed in handling them. Others are objectionable because they are tacky masses which can be incorporated into rubber compounds only with difficulty. Still other compounds of the class can be manufactured only from relatively expensive ingredients and the costof manufacturing them is, therefore, prohibitive. 1

This invention involves the discovery that certain azo-amino compounds, when incorporated in rubber, have excellent antioxidant or age-retarding properties. These compounds may be manufactured from relatively inexpensive ingredients. They are nonodorous and of crystallme character andmay, therefore, be introduced into rubber com 7 pounds with 'a minimum of inconvenience.

These amino-azo compounds are embraced by the type formula RN=N- R NH in which R and R are hydrocarbon radicals.

Application filed March 20, 1928. Serial 'No. 263,225.

One compound of the class which is found to beparticularly effective as an antioxident or age-retarder is lp-amino azo benzene (GGH5N=3NO6H4N V This" compound may be prepared by any convenient method known in the chemical arts. The method outlined on page 265 of Practical Methods of Organic Chemistry by Gattermann (translated by Schober and Babasinian), published by the -MacMillari" Co. of "New York, is an example of one suchmethod. A

also'embraced within the scope of the invent-ion i's p-amino azo naphthalene which may be prepared by methods analogous to those outlined for the preparation ofYp-amino azo benzene. V e a Azo compounds embraced within the scope of this invention may be employed as antioxidants inmost of the standard formulae. The following is the formula ofa compound in which substances of the class just discussed have been observed to be particularly eflicient as antioxidants Parts second compound of the same class which In the above formula,,hexamethylene tet strength and elasticity immediately after vulcanization and before any.appreciableaging.

1 formulae without appreciably upsetting'the Other samples, similarly vulcanized, Were subjected to aging in an oxygen bomb for a period of six days at a temperature of 50 C.

Rubber containing 1 part p-amino azo benzene I Stress in kgsl/cm at I,

Time Per cent Per cent of cure 7 glongaincrease in min- 500 700 ion at in utes elong aelonggbreak weight tion tion a After aging six days in Oabomb at 50 (land 150$ per-sq. in.

30 v 15. 5 ,105 fete T .07 50 25 94 '150 785 ..09 c 70 37 i145 v170 730 .23

Rubber containing 1 part p-"amino azo napthalin 1a 37 900 50.: I ,21 70 145 825 I After a ing six days in oz b mb at Ofand 150;!

per sq. m

ItWlll be. evident from the preceding tables that'compounds containing either p.-

amino azo benzene or p-amino azo napthalin are but little afiectedby the action of oxygen even when sub ected to the relat vely severe conditions existing during the tests. 1 Indeed, in certain instances it would appear that the quality of the product, was some- What. improved by artificial aging' Under similar circumstances, compounds containing no antioxidant would have been reduced to resin-like masses. possessing little or 'no elasticity orjtensile strength. The compounds discussed have little 'or no power as accelerators andthey ay there'fore'be introduced into most of the standard rubber ous minor modification s 'may be made therein WVltllOut departing from the spirlt of the invention or from the scope of the ap )ended claims,'wherein'I intend to claim allfeatures of patentable novelty inherent in the invention i What Iblaim is: I

1. A method of treating rubber which comprises incorporating therein a compound RN==NR NH in which R and R are 'phe nyl radicals.

2. A method of treating rubber which comprises incorporating therein an amino azo benzene. p c

3. A rubber product that has been vulcanized in the presence of a material having the following structural formula: R NH in which R and R represent benzene radicals. 1

4. A rubber product that has been vulcanized in the presence of amino azo benzene.

5. A method of preserving rubber which comprises vulcanizing it in the presence of a material having the following structural formula: RN=NR NH in which R and R are radicals selected from the benzene series. Y a v 6. A rubber product that has been vulcanized in the preseneeof a material having the formula BN=NR NH in'vvhich and R are radicals selected from the benzene series.

7. A method of preserving rubber which comp ises subjecting it to vulcanization in the presence .of. p-amino azo benzene.

. 8. Arubber product that has been vulcanized in the presence of p-amino azo benzene.

9. A rubber product that has been vulcanized in the presence of a material having the formula RN=NR in which is a -ben-- zene radical containing only carbon and hydrogen and R is an ammonia substituted benzene group consisting entirely ofca rbon,

zation and an amino-azo aromatic hydrocarbon l2. The method of. preserving rubber which comprises vulcaniz'ing rubber, in the presence of anactlve accelerator of vulcan zation and p-amino'azo benzene. c

'13. A rubber product which has been V111.

V canized in the presence of an active accelerator of vulcanization and a material RN.=NR NH wherein R and R are selected from a group embracing the members of thebenzene series. Q v In witness whereof, I have hereunto signed my name at Akron, inthe county, of Summit and State of Ohio, U. S. this 19th day of March, 1928. a I

r JAN TEPPEMA. 

